diff --git a/src/ca/iocinf.h b/src/ca/iocinf.h
index 19b855534..ebfc8f135 100644
--- a/src/ca/iocinf.h
+++ b/src/ca/iocinf.h
@@ -251,6 +251,7 @@ class baseNMIU;
 class tcpiiuPrivateListOfIO {
 private:
     friend tcpiiu;
+    friend netiiu; // used to install subscriptions when not connected
     tsDLList < class baseNMIU > eventq;
 };
 
@@ -513,6 +514,7 @@ public:
     virtual int readNotifyRequest ( nciu &, cacNotify &, unsigned type, unsigned nElem );
     virtual int subscriptionRequest ( netSubscription &subscr, bool userThread );
     virtual int subscriptionCancelRequest ( netSubscription &subscr  );
+    virtual int installSubscription ( netSubscription &subscr );
     virtual void unistallSubscription ( nciu &chan, netSubscription &subscr );
     virtual void subscribeAllIO ( nciu &chan );
     virtual int createChannelRequest ( nciu & );
@@ -753,6 +755,7 @@ public:
     int clearChannelRequest ( nciu & );
     int subscriptionRequest ( netSubscription &subscr, bool userThread );
     int subscriptionCancelRequest ( netSubscription &subscr  );
+    int installSubscription ( netSubscription &subscr );
     void unistallSubscription ( nciu &chan, netSubscription &subscr );
 
     void hostName ( char *pBuf, unsigned bufLength ) const;
diff --git a/src/ca/nciu.cpp b/src/ca/nciu.cpp
index 9b8cd7888..6a1a475e8 100644
--- a/src/ca/nciu.cpp
+++ b/src/ca/nciu.cpp
@@ -353,22 +353,12 @@ bool nciu::searchMsg ( unsigned short retrySeqNumber, unsigned &retryNoForThisCh
 
 int nciu::subscriptionMsg ( netSubscription &subscr, bool userThread  )
 {
-    int status;
-    if ( this->f_connected ) {
-        status = this->piiu->subscriptionRequest ( subscr, userThread );
-    }
-    else {
-        status = ECA_NORMAL;
-    }
-
-    return status;
+    return this->piiu->subscriptionRequest ( subscr, userThread );
 }
 
 void nciu::unistallSubscription ( netSubscription &subscr )
 {
-    if ( this->f_connected ) {
-        this->piiu->unistallSubscription ( *this, subscr );
-    }
+    this->piiu->unistallSubscription ( *this, subscr );
 }
 
 void nciu::incrementOutstandingIO ()
@@ -518,7 +508,7 @@ int nciu::subscribe ( unsigned type, unsigned long nElem,
     netSubscription *pSubcr = new netSubscription ( *this, 
         type, nElem, mask, notify );
     if ( pSubcr ) {
-        int status = this->piiu->subscriptionRequest ( *pSubcr, true );
+        int status = this->piiu->installSubscription ( *pSubcr );
         if ( status != ECA_NORMAL ) {
             pSubcr->destroy ();
         }
diff --git a/src/ca/netiiu.cpp b/src/ca/netiiu.cpp
index 734c2d2d5..163a44ce4 100644
--- a/src/ca/netiiu.cpp
+++ b/src/ca/netiiu.cpp
@@ -190,7 +190,7 @@ int netiiu::clearChannelRequest ( nciu & )
     return ECA_DISCONNCHID;
 }
 
-int netiiu::subscriptionRequest ( netSubscription &, bool )
+int netiiu::subscriptionRequest ( netSubscription &subscr, bool )
 {
     return ECA_NORMAL;
 }
@@ -200,8 +200,17 @@ int netiiu::subscriptionCancelRequest ( netSubscription & )
     return ECA_DISCONNCHID;
 }
 
-void netiiu::unistallSubscription ( nciu &, netSubscription & )
+int netiiu::installSubscription ( netSubscription &subscr )
 {
+    epicsAutoMutex autoMutex ( this->mutex );
+    subscr.channel ().tcpiiuPrivateListOfIO::eventq.add ( subscr );
+    return ECA_NORMAL;
+}
+
+void netiiu::unistallSubscription ( nciu &, netSubscription &subscr )
+{
+    epicsAutoMutex autoMutex ( this->mutex );
+    subscr.channel ().tcpiiuPrivateListOfIO::eventq.remove ( subscr );
 }
 
 void netiiu::hostName ( char *pBuf, unsigned bufLength ) const
diff --git a/src/ca/tcpiiu.cpp b/src/ca/tcpiiu.cpp
index 6bd1b4150..97622eece 100644
--- a/src/ca/tcpiiu.cpp
+++ b/src/ca/tcpiiu.cpp
@@ -1679,25 +1679,25 @@ int tcpiiu::createChannelRequest ( nciu &chan )
 
 int tcpiiu::clearChannelRequest ( nciu &chan )
 {
+    int status;
+
     if ( this->sendQue.flushThreshold ( 16u ) ) {
         this->flushToWire ( true );
     }
 
     epicsAutoMutex autoMutex ( this->mutex );
 
-    int status = this->sendQue.reserveSpace ( 16u );
-    if ( status == ECA_NORMAL ) {
-        if ( ! chan.verifyConnected ( *this ) ) {
-            status = ECA_DISCONNCHID;
-        }
-        else {
-            baseNMIU *pNMIU;
-            while ( ( pNMIU = chan.tcpiiuPrivateListOfIO::eventq.get () ) ) {
-                baseNMIU *pFound = this->ioTable.remove ( *pNMIU );
-                assert ( pFound == pNMIU );
-                pNMIU->subscriptionCancelMsg ();
-                delete pNMIU;
-            }
+    baseNMIU *pNMIU;
+    while ( ( pNMIU = chan.tcpiiuPrivateListOfIO::eventq.first () ) ) {
+        delete pNMIU;
+    }
+
+    if ( ! chan.verifyConnected ( *this ) ) {
+        status = ECA_DISCONNCHID;
+    }
+    else {
+        status = this->sendQue.reserveSpace ( 16u );
+        if ( status == ECA_NORMAL ) {
             this->sendQue.pushUInt16 ( CA_PROTO_CLEAR_CHANNEL ); // cmd
             this->sendQue.pushUInt16 ( 0u ); // postsize
             this->sendQue.pushUInt16 ( 0u ); // dataType
@@ -1741,9 +1741,6 @@ int tcpiiu::subscriptionRequest ( netSubscription &subscr, bool userThread )
             status = ECA_NORMAL;
         }
         else {
-            this->ioTable.add ( subscr );
-            subscr.channel ().tcpiiuPrivateListOfIO::eventq.add ( subscr );
-
             // header
             this->sendQue.pushUInt16 ( CA_PROTO_EVENT_ADD ); // cmd
             this->sendQue.pushUInt16 ( 16u ); // postsize
@@ -1962,10 +1959,12 @@ void tcpiiu::subscribeAllIO ( nciu &chan )
         tsDLIterBD < baseNMIU > iter = 
             chan.tcpiiuPrivateListOfIO::eventq.first ();
         while ( iter.valid () ) {
+            this->ioTable.add ( *iter );
             iter->subscriptionMsg ();
             iter++;
         }
     }
+    this->flush ();
 }
 
 // cancel IO operations and monitor subscriptions
@@ -1988,13 +1987,20 @@ void tcpiiu::disconnectAllIO ( nciu &chan )
     }
 }
 
+int tcpiiu::installSubscription ( netSubscription &subscr )
+{
+    {
+        epicsAutoMutex autoMutex ( this->mutex );
+        subscr.channel ().tcpiiuPrivateListOfIO::eventq.add ( subscr );
+        this->ioTable.add ( subscr );
+    }
+    return this->subscriptionRequest ( subscr, true );
+}
+
 void tcpiiu::unistallSubscription ( nciu &chan, netSubscription &subscr )
 {
     epicsAutoMutex autoMutex ( this->mutex );
-    if ( chan.verifyConnected ( *this ) ) {
-        baseNMIU *p = this->ioTable.remove ( subscr );
-        if ( p ) {
-            chan.tcpiiuPrivateListOfIO::eventq.remove ( subscr );
-        }
-    }
+    chan.tcpiiuPrivateListOfIO::eventq.remove ( subscr );
+    baseNMIU *pIO = this->ioTable.remove ( subscr );
+    assert ( pIO == &subscr );
 }
diff --git a/src/ca/tcpiiu_IL.h b/src/ca/tcpiiu_IL.h
index f40aae4b1..17808875a 100644
--- a/src/ca/tcpiiu_IL.h
+++ b/src/ca/tcpiiu_IL.h
@@ -47,11 +47,20 @@ inline SOCKET tcpiiu::getSock () const
 
 inline void tcpiiu::flush ()
 {
+    bool signalNeeded;
     {
         epicsAutoMutex autoMutex ( this->mutex );
-        this->flushPending = true;
+        if ( this->sendQue.occupiedBytes () ) {
+            this->flushPending = true;
+            signalNeeded = true;
+        }
+        else {
+            signalNeeded = false;
+        }
+    }
+    if ( signalNeeded ) {
+        epicsEventSignal ( this->sendThreadFlushSignal );
     }
-    epicsEventSignal ( this->sendThreadFlushSignal );
 }
 
 inline bool tcpiiu::ca_v44_ok () const